<?php
/**
 * Datasource connection manager
 *
 * Provides an interface for loading and enumerating connections defined in app/Config/database.php
 *
 * CakePHP(tm) : Rapid Development Framework (http://cakephp.org)
 * Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
 *
 * Licensed under The MIT License
 * For full copyright and license information, please see the LICENSE.txt
 * Redistributions of files must retain the above copyright notice.
 *
 * @copyright     Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
 * @link          http://cakephp.org CakePHP(tm) Project
 * @package       Cake.Model
 * @since         CakePHP(tm) v 0.10.x.1402
 * @license       http://www.opensource.org/licenses/mit-license.php MIT License
 */

App::uses('DataSource', 'Model/Datasource');

/**
 * Manages loaded instances of DataSource objects
 *
 * Provides an interface for loading and enumerating connections defined in
 * app/Config/database.php
 *
 * @package       Cake.Model
 */
class ConnectionManager {

/**
 * Holds a loaded instance of the Connections object
 *
 * @var DATABASE_CONFIG
 */
	public static $config = null;

/**
 * Holds instances DataSource objects
 *
 * @var array
 */
	protected static $_dataSources = array();

/**
 * Contains a list of all file and class names used in Connection settings
 *
 * @var array
 */
	protected static $_connectionsEnum = array();

/**
 * Indicates if the init code for this class has already been executed
 *
 * @var bool
 */
	protected static $_init = false;

/**
 * Loads connections configuration.
 *
 * @return void
 */
	protected static function _init() {
		include_once APP . 'Config' . DS . 'database.php';
		if (class_exists('DATABASE_CONFIG')) {
			static::$config = new DATABASE_CONFIG();
		}
		static::$_init = true;
	}

/**
 * Gets a reference to a DataSource object
 *
 * @param string $name The name of the DataSource, as defined in app/Config/database.php
 * @return DataSource Instance
 * @throws MissingDatasourceException
 */
	public static function getDataSource($name) {
		if (empty(static::$_init)) {
			static::_init();
		}

		if (!empty(static::$_dataSources[$name])) {
			return static::$_dataSources[$name];
		}

		if (empty(static::$_connectionsEnum[$name])) {
			static::_getConnectionObject($name);
		}

		static::loadDataSource($name);
		$conn = static::$_connectionsEnum[$name];
		$class = $conn['classname'];

		if (strpos(App::location($class), 'Datasource') === false) {
			throw new MissingDatasourceException(array(
				'class' => $class,
				'plugin' => null,
				'message' => 'Datasource is not found in Model/Datasource package.'
			));
		}
		static::$_dataSources[$name] = new $class(static::$config->{$name});
		static::$_dataSources[$name]->configKeyName = $name;

		return static::$_dataSources[$name];
	}

/**
 * Gets the list of available DataSource connections
 * This will only return the datasources instantiated by this manager
 * It differs from enumConnectionObjects, since the latter will return all configured connections
 *
 * @return array List of available connections
 */
	public static function sourceList() {
		if (empty(static::$_init)) {
			static::_init();
		}
		return array_keys(static::$_dataSources);
	}

/**
 * Gets a DataSource name from an object reference.
 *
 * @param DataSource $source DataSource object
 * @return string|null Datasource name, or null if source is not present
 *    in the ConnectionManager.
 */
	public static function getSourceName($source) {
		if (empty(static::$_init)) {
			static::_init();
		}
		foreach (static::$_dataSources as $name => $ds) {
			if ($ds === $source) {
				return $name;
			}
		}
		return null;
	}

/**
 * Loads the DataSource class for the given connection name
 *
 * @param string|array $connName A string name of the connection, as defined in app/Config/database.php,
 *    or an array containing the filename (without extension) and class name of the object,
 *    to be found in app/Model/Datasource/ or lib/Cake/Model/Datasource/.
 * @return bool True on success, null on failure or false if the class is already loaded
 * @throws MissingDatasourceException
 */
	public static function loadDataSource($connName) {
		if (empty(static::$_init)) {
			static::_init();
		}

		if (is_array($connName)) {
			$conn = $connName;
		} else {
			$conn = static::$_connectionsEnum[$connName];
		}

		if (class_exists($conn['classname'], false)) {
			return false;
		}

		$plugin = $package = null;
		if (!empty($conn['plugin'])) {
			$plugin = $conn['plugin'] . '.';
		}
		if (!empty($conn['package'])) {
			$package = '/' . $conn['package'];
		}

		App::uses($conn['classname'], $plugin . 'Model/Datasource' . $package);
		if (!class_exists($conn['classname'])) {
			throw new MissingDatasourceException(array(
				'class' => $conn['classname'],
				'plugin' => substr($plugin, 0, -1)
			));
		}
		return true;
	}

/**
 * Returns a list of connections
 *
 * @return array An associative array of elements where the key is the connection name
 *    (as defined in Connections), and the value is an array with keys 'filename' and 'classname'.
 */
	public static function enumConnectionObjects() {
		if (empty(static::$_init)) {
			static::_init();
		}
		return (array)static::$config;
	}

/**
 * Dynamically creates a DataSource object at runtime, with the given name and settings
 *
 * @param string $name The DataSource name
 * @param array $config The DataSource configuration settings
 * @return DataSource|null A reference to the DataSource object, or null if creation failed
 */
	public static function create($name = '', $config = array()) {
		if (empty(static::$_init)) {
			static::_init();
		}

		if (empty($name) || empty($config) || array_key_exists($name, static::$_connectionsEnum)) {
			return null;
		}
		static::$config->{$name} = $config;
		static::$_connectionsEnum[$name] = static::_connectionData($config);
		$return = static::getDataSource($name);
		return $return;
	}

/**
 * Removes a connection configuration at runtime given its name
 *
 * @param string $name the connection name as it was created
 * @return bool success if connection was removed, false if it does not exist
 */
	public static function drop($name) {
		if (empty(static::$_init)) {
			static::_init();
		}

		if (!isset(static::$config->{$name})) {
			return false;
		}
		unset(static::$_connectionsEnum[$name], static::$_dataSources[$name], static::$config->{$name});
		return true;
	}

/**
 * Gets a list of class and file names associated with the user-defined DataSource connections
 *
 * @param string $name Connection name
 * @return void
 * @throws MissingDatasourceConfigException
 */
	protected static function _getConnectionObject($name) {
		if (!empty(static::$config->{$name})) {
			static::$_connectionsEnum[$name] = static::_connectionData(static::$config->{$name});
		} else {
			throw new MissingDatasourceConfigException(array('config' => $name));
		}
	}

/**
 * Returns the file, class name, and parent for the given driver.
 *
 * @param array $config Array with connection configuration. Key 'datasource' is required
 * @return array An indexed array with: filename, classname, plugin and parent
 */
	protected static function _connectionData($config) {
		$package = $classname = $plugin = null;

		list($plugin, $classname) = pluginSplit($config['datasource']);
		if (strpos($classname, '/') !== false) {
			$package = dirname($classname);
			$classname = basename($classname);
		}
		return compact('package', 'classname', 'plugin');
	}

}
